The hospital building and the chapel was designed by the British architect Frederick Wheeler. It was arranged as a sanatorium with the wards following a semi circle shape either side of a central staircase.[2]

The first patients arrived at the hospital in September 1904. During the First World War, soldiers were treated there and at the outbreak of the Second World War Mount Vernon became a general hospital.[2] In 1967, The Marie Curie Hospital, which provided cancer services, moved to Mount Vernon, Northwood.

The Paul Strickland Scanner Centre opened in 1985 and was officially opened by the Duchess of Kent on 20 March 1986. This centre provides specialist imaging facilities using high quality equipment.[3]

The hospital was also home to the Gray Laboratory which was founded in the 1950s, and the old hospital chapel which includes art nouveau designs, was converted into a library for the Gray Cancer Institute in 1988.[2]

In 2009 a new treatment centre opened. This provides surgery facilities in four new operating theatres. There is also a new outpatients department located in the treatment centre.[4]